Self-regulating dynamo-electric machine



W. HOLT.

SELF REGULATING DYNAMO ELECTRIC MACHINE.

APPLICATION FILED was. 1920.

'1 ,377,074, Patented May 3, 1921.

W 74666 66 I flue zfoi- UNITED STATES,

PATENT OFFICE.

WILLIAM HOLT, OF BIRMINGHAM, ENGLAND, ASSIGNOR OF ONE-HALF TO BROL'I.

LIMITED, OF BIRMINGHAM, ENGLAND. I 1

SELF-BEGULATIN G DYNAMO-ELECTRIC MACHINE.

7 '0 all whom it may concern:

Be it known that I, WILLIAM HOLT, subject of the King of Great Britain,residing at Birmingham, England, have invented certain new and usefulImprovements in Self- Regulating Dynamo-Electric Machines, of which thefollowing is a specification.

This invention relates to variable-speed self regulating dynamo electricmachines employed in connection with electric lighting systems ofmotor-driven vehicles, railway trains and the like, said machines beingused in conjunction with a battery of accumulators, and being of thattype in which supplementary poles are provided between mentary brush onone side of the respectivemain pole and a main brush on the other sideof said main pole; but according to the present invention the mainexcitation coils are connected directly across the supplementarybrushes.

The accompanying drawing is a diagrammatic representation of a machinewhich is in accordance with the present invention. The dynamo comprisesmain poles a, and unwound supplementary poles I) situated mid-waybetween the main poles, these supplementary poles being adapted toreceive the cross-magnetization of the armature 0. Main brushes d, alare situated u on the leading side of the supplementary pq es, and uponthe opposite side of said poles supplementary brushes 6, 6 are provided.The main poles a, a, are excited by means of shunt coils'f, arranged inseries and connected direct y across the supplementary brushes e, e, asshown. If the speed of the machine increases, the

difference of potential between the supple Specification of LettersPatent.

' -'wltnesses.

Patented May 3, 1921.

Application filed January 5, 1920. Serial No. 349,561.

mentary brushes 6, e is reduced, whereby the magnetizing effect of theexciting coils f, f, is diminished, thus weakening the main field andtending to keep the current output constant. The output curve may alsobe varied by means of series coils on the supplementary poles. I

If desired, the salient supplementary poles may be dispensed with bybringing the sides of the magnet frame close to the armature.

Although the invention has been described with reference to a. bi-polarmachine, it is obvious that the invention is equally applicable tomulti-polar machines.

Having fully described my invention, what I desire to claim and secureby Letters Patent is l. A self-regulating dynamo-electric machinecomprismg main poles and supplementary poles, a main brush and asupplementary brush upon opposite sides of each supplementary pole, andexcitation windings on the main poles connected directly across thesupplementary brushes, substantially as described.

2. A self-regulating dynamo-electric machine comprising main poles andsupplementary poles, a main brush and a supplementary brush uponopposite sides of each supplementary pole, said supplementary brushesbeing outside of the lnfluence of the main magnetic field, and excitingwmdings on the main poles connected directly across said supplementarybrushes, substantially as described.

3. A self-regulating dynamo-electric machine comprising main poles,supplementary poles located between said main poles and adapted toprovide a path for the crossfield independent of the main magneticfield, main brushes, supplementary brushes between said main andsupplementary poles influenced solely by the cross-magnet1zation, andexciting windings on the main poles connected directly across saidsupplementary brushes, substantially as described.

In testimony whereof I have hereunto set my hand in presence of twosubscribing WILLIAM HOLT.

I Witnesses:

W. L. SKERRE'I'I, H. O. PBA'I'I.

